Electrical discharge device



1943- w. w. ElTEL ET AL 2,334,397

ELECTRICAL DISCHARGE DEVICE Filed Feb. 11, 1942 IlL g.Z

INVENTORS' ILL/AM PV- i/TEL QZZZ CZ A-M-iCdllgiiiH THEIR ATTORNEY Patented Nov. 16, 1943 fornia r anama-liaising 11, 1942', Serial No. 430,389 l rnaa K Ourt'invention 7 relates ilto a discharge device such 'as sa thermionicf'tube; and more' particu- 3 to a mounting structure for an electrode 1 in' the tube. v

It is among the objects of our invention to provide improved means for supporting an elec- 7 comprises a tubular arm trode on a lead extending through a stem of an envelope.

Another object is to provide means for shielding the stem against electron bombardment and heat radiation. Q

A further object is to provide 'animproved lead adapted for directing a cooling fluid into the-stem. I

The invention possesses other v objects and features of advantage, some of which, with the foregoing, will be set forth in'the following description of our invention. It is to be under-.

stood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments thereof within. the scope of the claims. I

Referring to the drawing:

Figure 1 is a side view,. partly in section and partly in elevation, showing a grid mounting structure embodying the improvements invention; and.

Figure 2 is an axial sectional view showing a modified structure.

In terms of broad inclusion, our electrical discharge device comprises an envelope having a stem, a lead extending through the stem, an

of our electrode, a shield for the stem, and means for supporting the electrode and shield on the lead. An improved lead is also provided for a cooling fluid into the stem. t

In greater detail, and referring to Figure-1 of the drawing, our device comprises a, glass endirecting fa-saw t leads 'il-l .ofsay copper. Copper .IlSa -.good ther tz-n'tal conductorl and the I extension leads: serve ato conduct heat rapidly out of the stem to terminal button l2 lying outside the stem cavity.

The mounting structure for the electrode I3, preferably of tantalum, disposed coaxially with the stem and having an upwardly bent arcuate flange I4 welded to the circumference of base ring 6 of the grid. Since a cathode disposed within the grid usually has downwardly extending leads, the lower forward portions of tubular arm I3 are'preferably cut away along the line It to give clearancefor the cathode leads. Arm l3 is supported on leads 8 by a cup-shaped mounting plate I1, preferably of tantalum,welded to the ends of the leads and disposed transversely within the arm with its flanged edge welded to the arm. This structure provides a mechanically strong support for the electrode; the tubular shape of the arm not onlyadding to the rigidity of the support, but also providing a large radiating surface for dissipating heat before it'reaches the steam by conduction. In order to increase radiation from the arm its outer surface is preferably roughened.

The stem structure is further protected against electron bombardment and heat radiation from the electrodes by a shield l8. This shield is also supported'on leads 8; preferably being welded to the rear end of arm l3 so that the shield forms an extension of the arm. The tubular shield projects rearwardly and preferably flares outwardly to provide a protective velope 2 having a reentrant stem 3 for supporting an electrode 4 such as a grid. The envelope may be of any suitable shape, say a spherical bulb; and in the device illustrated the stem projects from a side of the envelope at an angle to the axis of electrode or grid 4. For purposes of illustration we show a grid having a plurality of vertical wires welded to a base. ring 6 about which is disposed a heat radiating flange 1.

' A plurality of say three tungsten leads 8 extend through the stem, and are sealed in a trilobed pinch 9 at the nose of the stem. These leads project from the stem, with the inner ends terminating in a plane lying transversely hood about the leads and stem,' withthe inner surface of the shield freely spaced from the stem. Since the shield. does not form part of the electrical conducting path between leads ,8 and the electrode, any suitable metal such as nickel may be employed for it. The outer surface of the shield is left shiny to provide a heat reflector.

By the structure thus described, the stem and the leads projecting from it are protected against electron bombardment and heat radiation from the electrodes. Furthermore, the shield which is exposed to the bombardment and radiation is thermally isolated from the ,stem since the only of the stem axis." The outer ends of leads 8' terminate within the stem shortlyv below the press and are connected to heavier extension conducting path between the two is the roundabout one through the leads. The stem is thus kept sufliciently cool toprevent cracking the glass at the seal.

v Figure 2 shows a modified construction in which asingle heavy tungsten lead i9 extends through a seal 2i on stem 3. A flanged collar 22 v of tantalum is weldedon the inner end of the lead lead and carrying said electrode, and a tubular extension on the arm projecting 'rearwardly alongside the lead and providing a protective hood for the stem.

2. An electrical discharge device comprisingvan' envelope having a stem, a grid in the envelope and disposed about an axis angularly disposed to the axis of said stem} a lead projecting from the stem, a tubular shield embracing'the stem and providing a protective hood therefor, and means 7 supporting the shield and grid on said lead.

through the mouth of the stem carries away heat and thus further cools the stem; Air may be) supplied from any 'suitablesource; and is deliv ered through a suitable tube connected to the outer end of the lead.

We claim: I t 1. An electrical discharge device comprising an envelopehaving a stem, an electrode, a'lead for -the"electrode projecting from' the stem, a tubular .ar n mounted on and extending forwardly of the 3. An electrical discharge device comprising anv envelope having a stem, an electrode in the envelope; arlead projecting from the stem, an arm extending forwardly of the lead and carrying said electrode, a shield extending rearwardly alongside the lead and providing a protective hood for the stem', said arm and shield being arcuate in cross-section, and means supporting said arm and shield on. said lead.

- JACK A.-McCULLOUqH-. 

